The impact of insecticide-treated school uniforms on dengue infections in school-aged children: study protocol for a randomised controlled trial in Thailand

Abstract

BackgroundThere is an urgent need to protect children against dengue since this age group is particularly sensitive to the disease. Since dengue vectors are active mainly during the day, a potential target for control should be schools where children spend a considerable amount of their day. School uniforms are the cultural norm in most developing countries, worn throughout the day. We hypothesise that insecticide-treated school uniforms will reduce the incidence of dengue infection in school-aged children. Our objective is to determine the impact of impregnated school uniforms on dengue incidence.MethodsA randomised controlled trial will be conducted in eastern Thailand in a group of schools with approximately 2,000 students aged 7–18 years. Pre-fabricated school uniforms will be commercially treated to ensure consistent, high-quality insecticide impregnation with permethrin. A double-blind, randomised, crossover trial at the school level will cover two dengue transmission seasons.DiscussionPractical issues and plans concerning intervention implementation, evaluation, analysing and interpreting the data, and possible policy implications arising from the trial are discussed.Trial registrationclinicaltrial.gov. Registration number: NCT01563640

Mitigating Diseases Transmitted by Aedes Mosquitoes: A Cluster-Randomised Trial of Permethrin-Impregnated School Uniforms

“…The sample size calculation based on the primary endpoint has been described in detail in the trial protocol [18]. We originally planned a cross-over design spanning two transmission seasons because dengue transmission can vary greatly between schools and seasons, which can to some extent be controlled for by a cross-over design.…”

Theoretical impact of insecticide-impregnated school uniforms on dengue incidence in Thai children

“…(14), if we assume the annual incidence of dengue infection is 5% in Thai children (14, 23), the force of infection at this moment is 1.41×10 −4 cases per person-years. Assuming that a given proportion of children are expected to wear the insecticide-impregnated clothes during their school period, and the proportion of school time (that is the school time in hours divided by 24 hours) children wear the uniform, we can estimate the impact of this strategy as dependent on the proportion of all the mosquitoes’ bites that occur during that period.…”

“…Assuming that a given proportion of children are expected to wear the insecticide-impregnated clothes during their school period, and the proportion of school time (that is the school time in hours divided by 24 hours) children wear the uniform, we can estimate the impact of this strategy as dependent on the proportion of all the mosquitoes’ bites that occur during that period. Then, the expected proportion of seropositive some year after the intervention is calculated as:${trues}_H^{+}true(365daystrue)=1-e^{true[1-true(1.41\times {10}^{-4}(1-(A*B))true)365true]}\pm 1.96\sqrt{\frac{e^{true[-true(1.41\times {10}^{-4}(1-(A*B))true)365true]}true[1-e^{true[-true(1.41\times {10}^{-4}(1-(A*B))true)365true]}true]}{2,012}}$where 2,012 is the sample size of school children in the randomized controlled trial that is currently being conducted in eastern Thailand (14), A refers to a combination of the proportion of children that wear the uniform, the probability that the mosquitoes will get into contact with the insecticide-impregnated uniform and the proportion of school time children wear the uniform, while B is the proportion of mosquito bites that occur during school time.…”

“…Such a large community-based trial is currently in preparation in Thailand (13, 14). However, such trials are costly and difficult to implement and it will take some years before the results will be available.…”

Novel tools for the surveillance and control of dengue: findings by the DengueTools research consortium

“…We hypothesised that ISUs might reduce dengue infections [31]. We tested our hypothesis by setting up a large community-based trial to determine the reduction of dengue infections due to ISUs (InsectShield®) [32]. …”